In fact, the United States collects less corporate tax relative to the overall economy than almost any other country in the world.

And that's a more objective measure of tax burden. Different accounting rules around the world means what's counted as income in one country isn't counted in another -- that makes comparisons of tax rates misleading.

U.S. corporate tax collections totaled only 1.7% of GDP in 2009, the most recent year for which complete data is available, according to the Organization for Economic Cooperation and Development.

On that measure, the United States had the third lowest corporate tax burden, behind France and Germany. The worldwide average was 2.8%.

One reason U.S. corporate tax collections are low is that many U.S. small business owners file personal income tax returns, said Eric Toder, co-director of the nonpartisan Tax Policy Center.

In other countries, many small businesses pay both corporate and personal income tax. So a business owner in a country with a lower corporate tax rate could end up paying more than his U.S. counterpart.

Still most global corporate tax comparisons focus on tax rates. And by that score, the U.S. truly is No. 1. The U.S. corporate rate is 35%, the highest in the world in 2011, according to the OECD. The average rate in rest of the developed world is only 23%.

Include state and local taxes, and the U.S. ranks No. 2, just barely behind Japan.

U.S. companies also rank No. 2 when measured by so-called effective rates, the amount paid after the myriad of tax breaks. The Tax Foundation, a public interest group that is typically critical of high taxes, puts the effective rate for U.S. companies at about 26%.